docs: def new_message(self):
          """
          creates a new message, setting `type`, `source`, `ts`, `data`
          - `data` is initialized to an empty array
          """
          msg = {}
          msg['data'] = []
          msg['type'] = self.plugin_type
          msg['source'] = self.name
          msg['ts'] = (datetime.datetime.utcnow() - datetime.datetime(1970, 1, 1)).total_seconds()
          return msg